1. Field of the Invention
The present invention relates to an optical moving information measuring apparatus and a carrier system incorporating the apparatus. And more particularly, it relates to an optical moving information measuring apparatus which is used in a carrier system for carrying an object whose surface is not a mirror surface such as a recording paper in an image forming apparatus such as a printer or a copying machine, and optically obtains moving information such as moving speed or a moved distance of the object, that is, the moving object to be measured (referred to as the moving object hereinafter) without touching and a carrier system incorporating the above apparatus.
2. Description of the Prior Art
As shown in FIG. 19, a conventional optical moving information measuring apparatus comprising two distance measuring sensors 1 and 2 and one processing circuit part 3 is well known.
A principle of the distance measuring sensors 1 and 2 in the optical moving information measuring apparatus will be described with reference to FIG. 20. Each of the distance measuring sensors 1 and 2 comprises a light emitting part 4, a lens 5 for converging diffused light from the light emitting part 4, a light receiving part 7 for receiving reflected light from a surface of a moving object 6 and a lens 8 for converging the light toward the light receiving part 7.
Here, the light from the light emitting part 4 inputs to the surface of the moving object 6 in the substantially vertical direction and the reflected light from the input position passes through the lens 8 to converge to the light receiving part 7. In the light receiving part 7, PSD (a ratio of an output 1 and an output 2 is varied according to a position of the spot light converged on the light receiving surface) is used and the distance between the distance measuring sensor 1 (2) and the moving object 6 can be measured by using the fact that the output 1/output 2 is varied corresponding to the distance between the distance measuring sensor 1(2) and the moving object 6.
More specifically, as shown in FIG. 19, if the moving object 6 moves from left to right (in the direction shown by an outline arrow), an output is provided by the two distance measuring sensors 1 and 2 according to the concavo-convex condition of the surface of the moving object 6 (the distance between each of the distance measuring sensors 1 and 2 and the moving object 6 is varied by the concavo-convex amount). As shown in FIG. 21, according to the output signal waveform obtained at this time, the distance measuring sensor 2 of B is delayed (by time Δt) as compared with the distance measuring sensor 1 of A according to the moving speed of the moving object 6. The moving speed and the moved distance of the moving object 6 can be obtained by calculating this delay by the processing circuit part 3.
As another conventional technique, an optical moving information measuring apparatus of a laser Doppler system disclosed in Japanese Published unexamined patent application (Kôkai tokkyo kôhô) No. Hei 8(1996)-292263 or the like is well known.
According to this optical moving information measuring apparatus, laser beam output from a laser light source is divided into two by a beam splitter and the laser beam passed through the beam splitter is irradiated directly to a moving object and the laser beam reflected from the beam splitter is reflected by a mirror to be irradiated to the moving object. Then, the diffused light having different frequencies and reflected from the moving object moving at constant speed is detected by a light receiving sensor through a converging lens and a Doppler signal is taken out to be processed by predetermined signal processing, whereby the moving speed of the moving object is measured.
According to the former optical moving information measuring apparatus, since two pairs of the distance measuring sensors 1 and 2 each comprising the light emitting part 4, the light receiving part 7 and two lenses 5 and 8 are necessary, the number of parts is increased, a size is large and a manufacturing cost is high. In addition, if there is a concavo-convex configuration detected by the distance measuring sensors 1 and 2 as a difference of the distance on the surface of the moving object 6, it can be measured, but if the moving object has a relatively smooth surface (surface having fine concavo-convex configuration), the measurement is difficult.
According to the latter optical moving information measuring apparatus of the laser Doppler system, since the laser beam is divided into two, the number of parts is increased, the signal processing is complicated and the apparatus becomes large and expensive.